Conventional vehicle disc brakes employ a rotor fixed to and rotatable with a vehicle wheel having a pair of planar annular friction faces for receiving the pads of a spanning caliper mechanism. The rotor may be formed with a central hub or hat section for attachment to a wheel and two radially extending plates interconnected by ribs to allow airflow radially between the plates to better dissipate the heat generated during braking.
The conventional brake rotor design connects the braking surfaces to the hat section of the rotor via the outboard brake plate. Under elevated temperature usage the difference in thermal stress between the inboard and outboard brake plate causes a coning effect that distorts the brake plate surfaces resulting in non-uniform contact with the brake linings. One design solution implemented to reduce this thermal distortion is to connect the hat section to the inboard brake plate. The detriment to implementing this approach is that air cooling is reduced by closing off the ability of the vanes between the brake plates to dissipate the heat.
The optimal solution to balancing the thermal stress on the brake plates is to connect the brake plates to the hat section by the vanes. It has been asserted that the air flow through the vanes in this approach is comparable to the conventional brake plate attachment. One approach to this attachment method is shown in U.S. Pat. No. 6,164,423 which suggests a radially vented disc brake or similar rotor having inner and outer friction ring sections joined to one another and to a radially inner hub or hat section by a plurality of radially extending ribs or webs. Interspersed between these mounting ribs are another plurality of rib sections which join the ring sections to one another, but do not extend radially inwardly to join the ring sections to the hub. Each member of the first set of ribs function as a mounting rib interconnecting both ring sections with the hub while each rib of the latter set functions only to maintain separation or spacing of the ring sections. Cooling air may flow radially between one rib of each set. In another embodiment, there are two spacing ribs between each pair of mounting ribs and air may flow radially between one rib of each set as well as between two adjacent spacing ribs.
In U.S. Pat. No. 6,550,590 there is disclosed double venting arrangement for cooling a disc brake rotor. A central hub or hat section supports a solid support ring which, in turn, has vanes axially extending from each of its opposed faces to engage and support inboard and outboard braking rings or cheeks. One embodiment has the vanes on opposite sides of the support ring aligned with one another while another embodiment shows the vanes staggered with the vanes of one face angularly displaced from those of the other face by about one-half the angular spacing between adjacent vanes. In a third embodiment, the brake plates and support ring are slanted so that the air flow path is in a combined axial and radial direction. The patent suggests undercutting a hat surface region radially inward of the rings or brake plates axially close to the ribs to increase air flow into the vents between adjacent ribs.
Both of these patented arrangements have individual air flow paths adjacent ones of which are separated from one another by a mounting rib or vane.
It is desirable to provide an enhanced air flow path without deleteriously affecting structural integrity. It is also desirable to minimize thermally induced distortions such as coning without adversely reducing heat dissipation.